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NITED STA'BES PATENT OFFICE;

WALTER ALEXANDER, OF NEW YORK, N. Y.

Patent-ed Apr. 20, 1920.

Application filed February 8. 1917. Serial No. 147,329.

.J W W ah I ADHESIVE.

l W 1,337,381, Specification of Letters Patent.

No Drawing.

To all whom it may concern Be it known that I, 'ALTER ALEXANDER, a citizen of the l nitcd States, residing in the borou h of Manhattan. city, county, and State of h'e'w York, have invented certain new and useful Improvements in Adhesives.

of which the following is a specification.

I have discovered that the addition of a relatively small percentage of a boron de- 10 rivlive imparts to certain silicate compounds an extra body and an extra adhesiveness, and that. when they are used as adhesives or binding compounds. it increases the tensile stren th of the compound while I u c I imparting thereto the di" s W common to animal and v 'lhW 's Five usefully applied to the production of what may be termed a mineral adhesive which' is characterized both by an absence of the undesirable tendg cncy to deterioration inherent in animal and l/ i if vegetable adhesives. being free from liabil- X it) to fermentation, decay. or mold, and by the presence of the desired properties in such adhesives to a hitherto unattained degree.

My improved adhesive is formed from \ViltQY-SOllll)lg illkzllillfi. s ilicic and bgrig ig redieiits compounded as hereinafter set (Edi f In forming my mineral adhesive, l dissolve a water-soluble alkali base. for example, sodium carbonate, preferably with heat sufiicient to expedite the solution; to this I add a water-soluble boron salt, for example, borax, pre era y, as eca-hvdrate of mu etraborate, employing heat until an apparent solution is attained Flo this compound I add a water-soluble salt of silicon dioxid. for example. sodium silicate, and

mix by agitation under con muet eat, until the composition becomes perfectly clear. The composition produced will be a highly viscous adhesive of syrupy consistency 5 adapted for use as a mucilage, glue, or as an adhesive stifi'ener and binder, dependent upon its consistency, which may be thinned with water as desired. with'di'ymg properties s1m1 ar to adhesives having animal or vegetable origin.

As a water-soluble alkali bg se, Iemploy sodiiliu h droxid. either in the form of sodalveor caustic soda, l llt a less alkaline a lt 1 s usually preferable, such as commercial sodium carbonate. In producing my minera ac iesife', as it may be termed, on a commercial scale, either caustic sod-(1.01:7 the of commerce giv'EillfiffeiSults.

As a soluble silica salt, the various spigblc silicmyed; I have foiuid )Otl sodium silicate and potassium silicate to give excellent results, and in manufacturing practice I employ commercial sodium silicate solution. I

is a patel-soluble boron salt, any soluble horate iii 'he used, bu t for manu facturing piirposes commercial b orax is well adapted to produce the desired result.

As a specific example of the several formulae in which these alternative ingredients may be combined, I take:

10 grams of sodium carbonate. 10 grams of di v ese are mixed with heat suiiicient to dissolve the sodium carb onate.

5 grams of borax are then added to the solution and heating is continued until the borax appears to be dissolved.

100 grams of commercial l 'd sodium Q'ilicgte are then added to this solution and t 1e mixture is agitated by a continuous stirring. heat being continued until the composition becomes perfectly clear.

The resultant product may be packaged in any manner in which mucilage, glues, or the like adhesives are customarily prepared for the market, either in liquid or in solid granular form.

If any precipitate be found in the solution. the relationship between the alkali and silica ingredients must be slightly varied. Such precipitation is due to an excess of s i l i ca and may be readily overcome by increasing slightly the percentage of sodium carbonate or other alkali, or by slightly decreasing the percentage of borax. While there is some variation in the commercial silicates, borates, and carbonates, and while the several solutions may vary by reason of the fluctuating percentages of alkali or silica accordingly, even to the extent of altering the chemical and physical properties of the solutions, uniformity of product is attainable with the given formula by the correction of the precipitation, as described, as I have found that an increase in the amount of sodium carbonate or other alkali will overcome the precipitation and produce a clear solution. A adhesiv compound may be readily attained WhlCh 11 will stifl'en up to a syrupy consistency and will maintain its form for a very considerable length of time so long as it is kept from air, and will harden upon exposure, like other non-mineral glues.

While I have described the best method now known to me for making, compounding, and usin my improved adhesive, 1 do not Wish to limit my claimed discovery to the precise ingredients recited, since any water-soluble alkaline borate may be employed, as, for example, in addition to those previously named, otassium borate, borate of lime, sodium boigmloorat; etc, Wble allial me silicate, and the term dclil asil sed in the following claims is inclusive of both goalin m hydroxid and Haring thus described my invention, I

claim:

1. An adhesive composed of 80 parts of sodium silicate solution, 8 parts of sodium carbonate, 8 parts of water, and 4 parts of borax.

2. A clear transparent adhesive formed of 80 parts of soluble silicate solution, 4 parts of a water soluble borate, 8 parts additional water, and a sufficient quantity of soda (approximately 8 parts) to avoid precipitation.

WALTER ALEXANDER.

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